March/April 1996

Chestnuts

The chestnut is a unique nut-producing tree that may have some potential as an alternative crop for certain areas. Chestnut trees vary in growth habit, depending on the species, but generally make fairly large, spectacular trees.

Four common species of chestnut have been grown in North America. They exist as pure species, or more commonly, as hybrids of the various species, because they readily cross with one another. It is difficult, in many cases, to distinguish specific species and almost impossible to determine the parentage of the hybrids through visible identification.

Species

Castanea dentata: The American Chestnut was native to the Appalachian forests of the United States, from Maine to Georgia and Michigan to Louisiana. Trees are huge timber types that are tall, straight, and columnar, reaching a height of over 100 feet with trunk diameters of three to four feet. The nuts are small, about 100 to the pound, covered with a thick, pale fuzz, and compressed--two to three in the burr. They are said to be the sweetest and most flavorful of all the chestnuts. The species was virtually wiped out in the early 1900s by a fungus called Eudothia parasitica or Chestnut blight. The alien disease swept through the forest and caused one of our nation's worst ecological disasters. American chestnuts are believed to be resistant to oak root fungus.

Castanea sativa: The European Chestnut is native to the temperate mountains of Western Asia, Europe, and North America. Chestnuts growing in this area seem to be quite tolerant of less than ideal conditions. Trees are large and spreading, with a compact head; the nuts are much larger than in the American species. Nut quality is quite variable, depending on the individual variety. These are the imported nuts commonly seen in U.S. supermarkets.

Castanea mollissima: The Chinese Chestnut is the smallest tree of all the species (about 40 feet tall). It is native to northern and western China. The nuts are generally medium in size and of good eating quality. Trees bear at a young age (three years) and are the most resistant to chestnut blight.

Castanea crenata: The Japanese chestnut is native to China and Japan, where it grows into a dense, slender tree, attaining a height of about 50 feet. The tree is very resistant to most known diseases. Burrs usually contain three (but sometimes five to seven) large to very large nuts. Nut quality is often inferior to other species.

Varieties

There are several varieties that have been selected in each species group, and more recently, breeding programs have produced many hybrids. Following is a list of some of the varieties grown in the United States and their purported characteristics.

Colossal: (ExJ) Huge, sweet nuts (average 11 per pound) with a thick pellicle and some multiple embryos. Productive trees, modestly susceptible to blight. Proven productive in the San Joaquin Valley.
Crane: (C) Nuts average 32 per pound, shell is dark red, excellent edibility with a superior keeping quality.
Douglas Hybrid: (CxA) Good size nuts, late flowering and blight resistant.
Dunston Hybrid: (CxA) Large nuts of very good quality; trees are blight resistant.
Canby Black: (E) Productive vigorous with a high quality large nut.
Gellatly #1: (C) Productive tree with sweet, early nuts that fall free of the burr. Retain leaves through the winter.
Layeroka: (CxE) Early, productive, large sweet nuts that fall free of the burr. Timber growth habit, blight resistant, cold hardy, and pollen sterile.
Myoka: (CxE) Good producer of medium size nuts that stick in the burr, but the pellicle peels easily. Vigorous and good pollen producer, blight resistant.
Orrin: C) Upright, narrow, productive tree. Nuts have good flavor, size, and an attractive color. Excellent keeping quality.
Prolific: (E) Massive, wide, spreading tree; productive, fair quality nuts.
Revival TM: (AxC) Average 24 to 32 nuts per pound with a good flavor and easily peeled pellicle. Trees are large timber types that are early bearing and blight resistant.
Silverleaf: (E) Large, very sweet nut that peels easily. Proven in the San Joaquin Valley, blight susceptible.
Skookum: (CxE) Cross of Lyeroka and Myoka, vigorous tree with large sweet nuts
Skioka: (CxE) Produces 35 to 40 nuts per pound, of good quality. Productive tree with sterile pollen.
Sleeping Giant: (CxAx) Sweet, large nuts that fall free of the burr. Trees are vigorous, somewhat productive, and blight resistant.
Willamette: Produces 18 to 22 nuts per pound that are sweet and easy to peel. Smaller productive tree.

Flowers and Bearing Habit

Chestnuts have male (staminate) flowers, also called catkins, and female (pistillate) flowers that are attached to the lower portion of some of the catkins. Cross pollination is required since the pollen is often shed before pistillate flowers are receptive. Overlapping male and female bloom from two different varieties is required; pollen is wind transmitted. The cream colored nut "meats" are covered with a thin bitter membrane (pellicle) and dark brown, hard, leathery shell, encased in a prickly burr (involvere). The burr splits at maturity and may contain from one to seven nuts. Nut size, degree of burr separation from the shell, and ease of pellicle removal are very important quality characteristics.

Nut Characteristics and Uses

The chestnut is a grain growing on a tree. The nut contains about 40 percent carbohydrate, about 40 percent water, 5 to 10 percent protein, and less than 5 percent oil. It is similar to other starchy foods such as potatoes or rice and other grains.

Traditionally the main use in the United States has been for eating raw or roasted as in "chestnuts roasting in an open fire." The nut is very flavorful and sweet and can be used as an ingredient in turkey stuffing, sweet breads, cakes, soups, stir fry dishes, cereals, or ice cream. Candied nuts are common in Europe. Dried nuts can be ground into flour and used in diets for people with allergies to grains.

Current Production and Market Potential

Estimates of world production, export/import, and use statistics vary considerably with the source of the statistics. The following statistics are from a talk given in August, 1987, by Michael Burnett of the Chestnut Growers Exchange at the Pacific Northwest Chestnut Congress, Corvallis, Oregon.

Production

• 1.2 billion pounds produced worldwide.
• China produces about 40 percent.
• Italy, Turkey, Japan, and Korea each produce about 20 percent.
• Other producers include France, Spain, Portugal, Greece, and the U.S.
• U.S. production is less than 1 percent--about 250 to 400 tons.
• U.S. current production is on about 400 acres.
• California has about 135 acres of commercial production.
• Production ranges from 1 to 2.5 tons/acre in California.

Imports and Prices

Most of our imports are from Italy. The nuts are shipped by boat and are sometimes of inferior quality. We import 10 million pounds; about $20 million worth. Import prices range from $1.50 to $3.00/lb. (average $2.10/lb.).

Consumption

• 2 lbs. per capita in China.
• 1 lb. per capita in Europe.
• .05 lb. per capita in U.S.

The United States would need to produce chestnuts on 5,000 acres just to displace imports. Reduced transportation costs and improved local quality should help capture a market. There also seems to be a potential to increase consumption through marketing and promotion programs.

Chestnut Cultural Practices

Good judgment indicates that the culture of chestnuts parallels that of walnuts. Chestnuts need well-drained soil to survive and thrive. Deep alluvial soils would be optimum. Soil reaction or pH should be acid, as chestnuts have little tolerance for alkaline soils (optimum pH range 6 to 6.5). Trees could be closely planted to 20 x 20 ft., 25 x 25 ft., or 30 x 30 ft., depending on the tree form and willingness to remove every other tree when crowding occurs. The large timber form trees are less desirable for California nut production. Hedgerow plantings of 9 to 14 ft. x 18 to 25 ft. might work, as it does with some walnut varieties.
Irrigation is required for rapid tree establishment and will most likely improve yields on a competitive commercial basis. It is important to build a large, strong tree as soon as possible.
Chestnut trees most likely will require tree training when young to develop a good modified central leader scaffold system. Good light penetration into lower branches could become important for mature trees to maintain production throughout the tree. Alternate-year pruning may also be feasible.
Fortunately chestnuts are relatively free of pests. The major pests known to attack chestnuts are:

• Chestnut blight (rare in California)
• Armellaria (some species)
• Bud mite (eastern states)
• Gall wasp (southeastern states)
• Filbert worm (Oregon)
• Shothole borer (stressed trees)

Harvest and Storage of Chestnuts

No mechanical system of chestnut harvest has yet been perfected, but most likely would be essential to lower labor costs. Some existing harvesting techniques for other crops such as walnuts, filberts, and processing cherries seem to be adaptable to chestnuts. Chestnuts should be treated more like apples in storage than like other tree nuts. They must be cooled to 32° F as soon as possible. Chestnuts dry out even at high humidity, so protective packaging is needed. Mold inhibiting fungicides and controlled atmosphere storage would most likely improve chestnut quality in long term storage.

Propagation

Seedling trees are quite variable and definitely not acceptable for commercial production. Seedlings can, however, be used as rootstocks, but only with scion wood from the same tree of origin as the seedling, because of widespread graft incompatibility problems. Grafting of high quality scion varieties onto random seedling trees commonly produces a poor graft union in 1 to 10 years. The normal grafting methods used on other woody species are quite successful with chestnut, especially if callusing is enhanced by temperatures near 80° F, high relative humidity, good aeration, no light, and limited pressure (hot pipe technique). Self rooting the trees is perhaps the best procedure for mass production, through layering, cutting, or tissue culture.

Nurseries Selling Chestnut Trees

Raintree Nursery
391 Butts Road
Morton, WA 98356

Dave Wilson Nursery
Hughson, CA 95326
(209) 874-1821

Chestnut Hill Nursery
Rt. 1, Box 341
Alachua, FL 32615
(904) 462-2820

Sonoma Antique Apple Nursery
4395 Westwide Road
Healdsburg, CA 95448

Fowler Nurseries, Inc.
525 Fowler Road
Newcastle, CA 95658

Raintree & Northwood Nursery
28696 Cromer Road
Molalla, OR 97038

Burnt Ridge Nursery
432 Burnt Ridge Road
Onalaska, WA 98570
(206) 985-2873

Bear Creek Nursery
P.O. Box 411
Northport, WA 99157

Jersey Chestnut Farm
58 Van Duyne Avenue
Wayne, NJ 07470